Infiltration Growth and Crystallization Characterization of Single-Grain Y-Ba-Cu-O Bulk Superconductors

A series of single-grain Y-Ba-Cu-O (YBCO) bulk superconductors were fabricated using a modified infiltration growth (IG) technique, and the morphology feature associated with the inner crystallization structure of the samples was investigated in detail. Experimental observations indicated that YBCO single grains grew much larger with the increasing slow-cooling time. A bended a/c growth sector boundary was observed in the cross section of the YBCO sample grown for 48 h, which resulted from the variations in the R-a/R-c ratio during the slow-cooling growth process, where R-a and R-c represent the growth rate in the a axis and c axis direction, respectively. In addition, different side surface morphology (SSM) patterns were presented for the samples fabricated with different processings, which originated from the difference in the crystallization structure of the YBCO single grains and could be divided into four groups. On the other hand, for a defined inner-crystallization structure, the changes of sample size (diameter or thickness) could also lead to various SSM styles. Finally, it was concluded that the comparison relationship between the ratio of sample radius and thickness with the ratio of R-a/R-c determined the final SSM pattern of the sample.